Mônica Campos Serra

Protective Effect of the Dental Pellicle against Erosive Challenges in situ

The acquired dental pellicle helps prevent erosion, but the protection level is unknown. This in situ study tested whether a two-hour pellicle protects against different erosive challenges by orange juice. Subjects wore palatal appliances loaded with either enamel or dentin specimens. Pellicle was allowed to form, or not (control), on the surfaces of the specimens intra-orally for 2 hrs before the erosive challenges of 0 (control), 10, 20, and 30 minutes’ duration. Specimens were randomly removed from the appliances after each challenge. Percentage of surface microhardness change (%SMC) was determined for the enamel specimens, and that of mineral loss and lesion depth for the dentin specimens. Enamel specimens with the pellicle showed a significantly lower %SMC, only after the 10-minute challenge. No protection was found for dentin. It was concluded that the acquired pellicle reduced dental erosion, but that this effect was limited to the less severe erosive challenge on enamel surfaces.

Caries Progression and Inhibition in Human and Bovine Root Dentine in situ

Since the use of bovine instead of human dentine to evaluate cariogenic and anticariogenic substances is not well established, this in situ study was conducted. Eleven volunteers wore palatal acrylic devices containing 4 dentine slabs (2 human and 2 bovine). Sucrose solution (20%) was dripped over all slabs 4 times a day, simulating a cariogenic challenge. Dentifrice slurries, fluoridated or not, were dripped over specified dentine slabs 3 times a day to evaluate caries reduction. After 14 days, the biofilm formed on the dentine slabs was collected for microbiological analysis. In dentine, mineral loss (ΔZ) and lesion depth (LD) were determined by cross-sectional microhardness and by polarized light microscopy, respectively. The total streptococci and mutans streptococci counts in the biofilm formed either on human or on bovine slabs, whether treated or not with fluoride dentifrice, were not statistically different. The ΔZ and the LD values of dentine treated with fluoride dentifrice were significantly lower than the values of dentine treated with non-fluoride dentifrice. The differences in the ΔZ and LD values between the human and bovine dentine were not statistically significant. The results suggest that bovine dentine can be used instead of human to evaluate caries development and inhibition.

Influence of the organic matrix on root dentine erosion by citric acid

This investigation was conducted in an attempt to clarify the role of the organic matrix in bovine dentine demineralisation by 1% citric acid. Dentine slabs (n = 15) were treated for 2 min with 10% sodium hypochlorite (NaOCl, a strong protein solvent), 2% glutaraldehyde (GDA, a protein fixative) or deionised water (DIW, as negative control) prior to each of 5 demineralisation periods of 30 min. The mineral loss (ΔZ), lesion depth (LD) and surface loss (SL) were determined after each period of demineralisation, by transverse microradiography. The NaOCl-treated group showed higher ΔZ and LD than the GDA- and DIW-treated groups. No differences between GDA and DIW groups were found. The ΔZ and LD profiles were explained by quadratic fits (r2 >0.80; p = 0.001) in all groups. SL was detected only in the NaOCl-treated group. The data suggested that the maintenance of the organic matrix in the lesion might be important to reduce the erosion progression rate.

Validity and Reproducibility of a Laser Fluorescence System for Detecting the Activity of White-Spot Lesions on Free Smooth Surfaces in vivo

The aim of the study was to determine the reproducibility and validity of DIAGNOdent in detecting active and arrested caries lesions on free smooth surfaces. Volunteers were selected from state schools of Piracicaba, São Paulo, Brazil. Overall, 220 lesions were clinically examined. Two specially trained (‘calibrated’) examiners performed both clinical and laser evaluations independently, and after a 1-week interval, the examinations were repeated. The intra-examiner agreement for the laser evaluation was substantial (ĸex1 = 0.79, ĸex2 = 0.71). There was almost perfect agreement between the two examiners for the clinical examination (ĸex1 = 0.95, ĸex2 = 0.85). The inter-examiner agreement showed substantial reproducibility (ĸ = 0.77) for the laser examination and almost perfect agreement (ĸ = 0.85) for the clinical evaluation. The validation criterion was the clinical examination of white spots, recorded as active or arrested. The sensitivity was 0.72 and the specificity was 0.73, which indicates that the DIAGNOdent was a good auxiliary method for detecting incipient caries lesions on free smooth surfaces. The utilization of both methods can improve the efficacy of caries diagnosis.

Bleaching agents with varying concentrations of carbamide and/or hydrogen peroxides: effect on dental microhardness and roughness.

PURPOSE To evaluate the effect of low and highly concentrated bleaching agents on microhardness and surface roughness of bovine enamel and root dentin. METHODS According to a randomized complete block design, 100 specimens of each substrate were assigned into five groups to be treated with bleaching agents containing carbamide peroxide (CP) at 10% (CP10); hydrogen peroxide (HP) at 7.5% (HP7.5) or 38% (HP38), or the combination of 18% of HP and 22% of CP (HP18/CP22), for 3 weeks. The control group was left untreated. Specimens were immersed in artificial saliva between bleaching treatments. Knoop surface microhardness (SMH) and average surface roughness (Ra) were measured at baseline and post-bleaching conditions. RESULTS For enamel, there were differences between bleaching treatments for both SMH and Ra measurements (p = 0.4009 and p = 0.7650, respectively). SMH significantly increased (p < 0.0001), whereas Ra decreased (p = 0.0207) from baseline to post-bleaching condition. For root dentin, the group treated with CP10 exhibited the significantly highest SMH value differing from those groups bleached with HP18/CP22, HP7.5, which did not differ from each other. Application of HP38 resulted in intermediate SMH values. No significant differences were found for Ra (p = 0.5975). Comparing the baseline and post-bleaching conditions, a decrease was observed in SMH (p < 0.0001) and an increase in Ra (p = 0.0063). CONCLUSION Bleaching agents with varying concentrations of CP and/or HP are capable of causing mineral loss in root dentin. Enamel does not perform in such bleaching agent-dependent fashion when one considers either hardness or surface roughness evaluations. CLINICAL SIGNIFICANCE Bleaching did not alter the enamel microhardness and surface roughness, but in root dentin, microhardness seems to be dependent on the bleaching agent used.

Potential agents to control enamel caries-like lesions

OBJECTIVES To assess whether pastes containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and calcium sodium phosphosilicate (CSP) control artificial caries lesion progression. METHODS Enamel slabs of bovine teeth were embedded in polyester resin and had their enamel surfaces serially polished, and tested for surface microhardness (SMH, 25 g, 5 s). Incipient caries-like lesions were pre-formed and specimens were evaluated by microhardness test (SMH(post-lesion)) and randomly assigned to five treatment groups (n=15): (1) regular dentifrice (RE, 1,100 ppm F); (2) dentifrice with calcium sodium phosphosilicate (CSP); (3) amorphous calcium phosphate stabilized by casein phosphopeptide (CPP-ACP); (4) CPP-ACP with 900 ppm F (CPP-ACP+F) and (5) control group-unexposed to any remineralizing agent. Treatments were applied five times, after the de-remineralization period in the cariogenic challenges. Post-treatments SMH measurements were conducted (SMH(post-treatment)). RESULTS ANOVA was applied for data evaluation and revealed a significant difference among the treatments (p=0.0161). Tukeys test was conducted and the percentage of mineral loss was calculated. Specimens exposed to CSP (7.1%), RE (6.7%) and CPP-ACP+F (3.8%) showed lower mineral loss than those that in the control group (-11.0%). CPP-ACP group (3.2%) differed from the control, CSP and RE groups. CONCLUSIONS Depending on the agent used, a remineralizing effect may be expected, which reflects in caries lesions progression.

Control of erosive tooth wear: possibilities and rationale

Dental erosion is a type of wear caused by non bacterial acids or chelation. There is evidence of a significant increase in the prevalence of dental wear in the deciduous and permanent teeth as a consequence of the frequent intake of acidic foods and drinks, or due to gastric acid which may reach the oral cavity following reflux or vomiting episodes. The presence of acids is a prerequisite for dental erosion, but the erosive wear is complex and depends on the interaction of biological, chemical and behavioral factors. Even though erosion may be defined or described as an isolated process, in clinical situations other wear phenomena are expected to occur concomitantly, such as abrasive wear (which occurs, e.g, due to tooth brushing or mastication). In order to control dental loss due to erosive wear it is crucial to take into account its multifactorial nature, which predisposes some individuals to the condition.

Viability of using enamel and dentin from bovine origin as a substitute for human counterparts in an intraoral erosion model

This study ascertained whether under dental erosion models that closely mimics the real-life situation enamel and root dentin from bovine origin would be reliable substitutes for human counterparts. Through a 2x2 crossover design, in a first trial, 14 volunteers wore a palatal device containing slabs of bovine and human enamel. Half of the participants ingested (4x daily, for 10 days) orange juice first, crossing over to mineral water, while the remainder received the reverse sequence. In a second trial, volunteers wore devices with slabs of bovine and human root dentin. Except for the duration of each intraoral phase, which lasted 2 rather 10 days, the experiment with root dentin run exactly as for enamel. Dental substrates were analyzed for surface microhardness. Two-way ANOVAs (α=0.05) indicated no difference between the microhardness values recorded for human and bovine enamel (p=0.1350), but bovine root dentin had lower microhardness compared to its human counterpart (p=0.0432). While bovine enamel can reliably substitute its human counterpart in in situ dental erosion models, bovine root dentin does not seem to be a viable alternative to the corresponding human tissue.

Cariostatic effect of fluoride-containing restorative systems associated with dentifrices on root dentin

OBJECTIVE The aim of this in vitro study was to evaluate the interaction between two sources of fluoride (restorative systems and dentifrices) in inhibiting artificial root caries development. METHODS One hundred and eighty tooth segments were embedded in polyester resin, and sanded flat. Cylindrical cavities 1.0mm-deep and 1.5mm-diameter were prepared in root dentin and randomly restored by fluoride-containing restorative systems: Ketac-fil/Espe (Ke), Fuji II LC/GC Corp (Fj), F2000/3M (F2), Surefil/Dentsply (Su) or a control: Filtek Z250/3M (Z2). Ten experimental groups were made to test the association among the five restorative systems and two dentifrices: with F(-) (Sensodyne Baking Soda) or without F(-) (Sensodyne Original) (n=18). After surface polishing, a 1mm-wide margin around the restorations was demarcated and initial dentin surface Knoop microhardness values (KHN(i)) were obtained. The specimens were submitted to a pH-cycling model, and to applications of slurries of dentifrice. Afterwards the final dentin surface Knoop microhardness values (KHN(f)) were measured. RESULTS The differences between KHN(i) and KHN(f), and the covariate KHN(i) were considered by the ANCOVA and Tukeys test (alpha=0.05). The interaction between restorative system and dentifrice was statistically significant (p=0.0026). All restorative systems provided some protection against artificial caries challenge when associated with the fluoride-containing dentifrice treatment. The means (standard deviation) of reductions in Knoop hardness values for systems associated with the fluoride-containing dentifrice were: Ke: 40.0(1.02)(a), Fj: 41.9(1.02)(b), F2: 43.3(1.04)(c), Su: 43.5(1.00)(c), Z2: 44.0(1.02)(c); and with the non-fluoride-containing dentifrice were: Ke: 42.9(1.02)(a), Fj: 44.7(1.01)(b), F2: 45.2(1.09)(bc), Su: 46.0(0.99)(c), Z2: 46.6(0.99)(c) (statistical differences were expressed by different letters). CONCLUSION The cariostatic effect shown by the fluoride-containing dentifrice could enhance that shown by Ketac-fil and Fuji II LC, and could mask that shown by F2000.

Microhardness and SEM after CO2 laser irradiation or fluoride treatment in human and bovine enamel

Background: It remains uncertain as to whether or not CO2 laser is able to hinder demineralization of enamel. The possibility to use bovine instead of human teeth on anticariogenic studies with laser has not yet been determined. Purpose: To compare the ability of CO2 laser and fluoride to inhibit caries‐like lesions in human enamel and to test whether a similar pattern of response would hold for bovine enamel. Study Design: Ninety‐six enamel slabs (2 × 2 × 4 mm) (48 from bovine and 48 from human teeth) were randomly distributed according to surface treatment (n = 12): CO2 laser, 5% sodium fluoride varnish (FV), 1.23% acidulated phosphate fluoride (APF) gel, or no treatment (control). Specimens were subjected to a 14‐day in vitro cariogenic challenge. Microhardness (SMH) was measured at 30 μm from the surface. For ultrastructural analysis, additional 20 slabs of each substrate (n = 5) received the same treatment described earlier and were analyzed by SEM. Results: ANOVA and Tukey test ascertained that CO2 laser promoted the least mineral loss (SMH = 252a). Treatment with FV resulted in the second highest values (207b), which was followed by APF (172c). Untreated specimens performed the worst (154d). SEM showed no qualitative difference between human and bovine teeth. APF and control groups exhibited surfaces covered by the smear layer. A granulate precipitate were verified on FV group and fusion of enamel crystals were observed on lased‐specimens. Conclusions: CO2 laser may control caries progression more efficiently than fluoride sources and bovine teeth may be a suitable substitute for human teeth in studies of this nature. Microsc. Res. Tech. 73:1030–1035, 2010.